Refiner stand

ABSTRACT

The invention concerns the provision of an improved stand, for a double-disk refiner, in which the temperature throughout can be maintained constant and obliqueness of the disks in relation to each other can be avoided. Bearing devices for shafts of the grinding disks are supported on trestles connected together by a plurality of beams which are arranged partly above and partly below a horizontal plane through the disks. The stand includes (a) ducts for circulation of a heat-transfer fluid through the stand and (b) means for keeping the fluid at constant temperature.

United States Patent 11 1 I 1 l 1 3,762,660 Berggstrom I Oct. 2, 1973 I 4] REFINER STAND 3,166,260 1/1965 Steiniger ct 24l/285 R 746 5 31965 F'.h 4 8 [75] Inventor: Jan lngemar Verner Bergstrom, 9 l B er 2 1/2 5 R X Sundsvall Sweden Primary ExaminerGranville Y. Custer, Jrv [73] Assignee: SCA Projekt Aktiebolag, AztorneyRalph E. Parker et a].

Sundsvall, Sweden [57] ABSTRACT [22] Filed 1971 The invention concerns the provision of an improved [2]] Appl No.: 190,201 stand, for a double-disk refiner, in which the temperature throughout can be maintained constant and bli ueness of the disks in relation to each other can be t P t D t 0 q [3O] Forelgn Apphca Ion "on y a a avoided. Bearing devices for shafts ofthe grinding disks Nov. 4, 1970 Sweden 14867/70 are supported on nestles connected together y a p rality of beams which are arranged partly above and [52] US. Cl ..B20421/228350R0 partly below a horizontal plane through the disks The [51] Int. Cl. 5c6 2/51 Stand includes (a) ducts for cimulation of a heap [58] Field of Search 241/2 5, 2 B, transfer fluid through the Stand and (b) means for 241/285 285 keeping the fluid at constant temperature. [56] References Cited 6 Claims, 10 Drawing Figures UNITED STATES PATENTS 2,563,783 9/195] Woodruff .4 241/285 R PAIENTEUIJBI 2197s PATENTEDDEI 2 ma SHEET 5 [IF 7 Illlll: IIHI REFINER STAND The present invention relates to disk refiners, in particular those comprising two separately driven, contrarotating grinding disks, so-called double-disk refiners. In a double-disk refiner the starting material for example chips, is introduced through a hole in the central part of one of the disks to a space between the two disks, whereupon the material during the rotation of the disks passes radially out between the disks, whereby the material is refined under the action of dentated zones fitted all around on the disks. The grinding disks are each mounted on a separate shaft driven by a motor.

According to previously known constructions the bearings of the shafts are mounted on a stand in the form of a bedding, which is mainly below a horizontal plane passing through the central axial line. Such a construction entails considerable problems, however, in view of unfavourable deformations of the stand during the operation of the refiner, caused on the one hand by the substantial grinding forces and on the other hand caused by the great development of heat.

It is extremely important for the result of the refining, that the grinding disks should be parallel regardless of the large forces which occur between the grinding disks during the refining, and regardless of the temperature expansions of the stand, which occur as a consequence of the heat developed during the refining.

If, as mentioned above, the stand is situated mainly below the horizontal plane through the axial line, that is to say the geometrical centre of gravity for a crosssection of the stand is located far below the axial line, the grinding forces will exert a deflecting effect on the stand, with the result that the parallelism of the grinding disks cannot be maintained. Since the grinding forces vary with different operating conditions, a varying angle between the grinding disks will also arise during the refining.

The energy which is supplied to the refiners is partly converted to heat when the material passes between the grinding disks. This heat diffuses largely through conduction and radiation into the stand. Naturally, the parts of the stand which are situated nearest the grind ing disks will assume. a higher temperature than the remaining parts of the stand. Moreover, the temperature distribution will vary in time as a function of the conditions of operation and the amount of energy that is supplied to the refiner. The uneven temperature distribution results in the stand altering its shape because of temperature expansion. In the previous constructions of the stand mentioned above the temperature will be highest in the upper part of the bedding, which means that the centre of the refiner will raise itself in relation to its ends. This means further that the parallelism between the disks will be greater at the top than at the bottom, which has an unfavourable effect on the result of the refining. Temperature differences may also arise between the two sides of the stand, with the consequence of further obliqueness of the disks.

The abovementioned problem is solved in accordance with the present invention by means of a new shaping ofthe stand, where the temperature can moreover be kept constant. The characteristics of the invention will be evident from the following patent claims.

The invention will be described by way of an embodiment with reference to drawings wherein FIG. 1 shows a double-refiner, FIG. 2 a cross'section along 2-2 in FIG. 1, FIG. 3 an outline diagram of the stand, FIG. 4 a cross-section along 44 in FIG. 3, FIG. 5 the distribution of forces in the stand, FIG. 6 the liquid circulation in the stand seen from the side, FIG. 7 the liquid circulation in thelower part of the stand seen from above; FIG. 8 is a fragmentary diagrammatic showing of the circulating system of the stand, FIG. 9 is a crosssectional view, on line 9 9 of FIG. 8, and FIG. 10 is a cross-sectional view, on line 10 10 of FIG. 8.

The refiner comprises a stand 1, in which are enclosed on the one hand two contra-rotating grinding disks 2,3 with corresponding shafts 4,5 and on the other hand two motors 6,7 for the driving of the shafts independently of each other. The shafts 4,5 are mounted in the bearings 8 11 which are fixed in the stand 1. For the feeding of the material intended for refining a feeding device 12, for example a worm conveyor, is present which delivers the material to the hole 13 in the central part of the one grinding disk 3, which hole opens out into the interspace between the grinding disks 2,3. The grinding disks are provided on their sides facing one another with dentated surfaces all around 14,15 in the form of a number of detachable plates which are fitted at a distance from the axial line C. The other grinding disk 2 is axially movable and adjustable by means of a special device (not shown in the drawings) for the regulation of the distance between the grinding disks.

The stand 1 consists in principle of four trestles 16-19, each of which supporting a bearing device 8 11 for the shafts 4,5 as seen in FIG. 3. These trestles are connected to one another by means of at least six beams 20-25 largely parallel with the axial line C, so that a cross-section of the stand encloses a surface whose centre of gravity is located close to the axial line C. The beams 20,21 which are arranged above the horizontal plane through the axial line C can be fitted so that they are detachable from the remaining parts of the stand, which makes possible good accessibility for work on the fixing points of the bearings. By virtue of the shaping of the stand the grinding forces will be distributed largely evenly over the four beams 20 23. Consequently the elastic elongation will be largely the same in all the beams, which means that the grinding forces will not affect the parallelism of the grinding discs. Owing to the great rigidity against deflection which the stand has as a result of this, the foundations can be made relatively small. It is also possible to use a resilient setting up of the stand, by which the vibrations which are transmitted to the floor are considerably reduced. Thus the plates 34, on which the feet 35 on the stand are placed, are made ofa resilient material such as rubber, plastic or the like. The resilient mounting is shown in FIGS. 1, 2, 8 and 9.

The distribution of forces in the stand is shown schematically in FIG. 5, where Q designates the force applied for grinding, P which in its magnitude corresponds to Q, designates the tensile force which is transmitted to the stand from the shafts 4,5, that is to say the grinding force, and P designates the combined tensile and bending force which arises in each of the four beams 20-23.

To prevent deformation of the stand as a result of temperature differences in the different parts of the stand it is proposed in accodance with the present invention that the stand should be provided with ducts 32,33 (see FIG. 7) where liquid is circulated, without any part of the liquid remaining stagnant in the stand. So as to maintain the stand at a constant temperature, the liquid temperature is chosen higher than the maximum temperature which during operation in the steady state would arise in any part of the stand without liquid circulation. As a result, the whole stand is made to assume the same temperature, and the deflection of the stand caused by temperature expansions caused by temperature differences in the stand, and the disadvantages associated therewith, are avoided. Thus the temperature of the stand can be maintained at stoppages so that controls or adjustments of the parallelism of the grinding disks can take place at operating temperature in psite of the disks being at standstill.

As shown in FIG. 7, in a vessel provided with an elecric heating device 26 and a thermostat, the liquid is heated to a preselected temperature and is kept constant at that temperature, for example by thermostatic control of the electric heater 26. A pump 27 attends to the liquid circulation. In the ducts 32,33, valves 28-31 are installed for the regulation of the liquid flow.

At short stoppages, for example for maintenance of repair, the liquid circulation need not be stopped. This is especially important when controls or adjustments of the parallelism of the grindings disks are carried out. Owing to the fact that the temperature of the stand is maintained by the circulating liquid, regardless of the development of energy at the refining, the adjustment of the disks may take place at operatng temperature in spite of the disks being at standstill.

The present invention is also suitable for so-called single refiners, that is to say refiners where a disk, provided with a dentated surface all around, is rotatable and workable against a fixed, similar dentated surfacev I claim:

I. Stand for a disk refiner comprising trestles for the support of bearing devices for aligned shafts which support a pair of parallel grinding disks said trestles being connected to each other by means of a number of beams,

at least two of said beams being arranged above a horizontal plane through said aligned shafts of the grinding disks and at least two of said beams being arranged below said plane, obliqueness of the disks in relation to each other as a result of grinding forces thereby being prevented;

ducts arranged in the stand, said ducts adapted to contain a fluid;

means for circulating fluid through said ducts; and

means for keeping the temperature of the fluid substantially constant, the temperature of the stand thereby being kept substantially constant for avoiding deflections of the stand as a result of temperature differences.

2. Stand as defined in claim 1, wherein the stand is resiliently supported on a base therefor.

3. Stand in accordance with claim 1 wherein the beams are parallel with said aligned shafts of the grinding disks and the cross-sectional center of gravity of the stand coincides with the axis of said aligned shafts of the grinding disks.

4. Stand in accordance with claim 1 wherein said at least two beams arranged above the horizontal plane are detachable from the remaining parts of the stand.

5. Stand as defined in claim 1, in which the means for keeping the temperature constant includes a source of heat and a thermostat controlling said heat source to maintain the temperature of the circulating fluid at a temperature which is higher than the maximum temperature which during operation in the steady state would arise in any part of the stand without fluid circulation.

6. Stand in accordance with claim 1, in which a pump is adapted to circulate the fluid through said stand 

1. Stand for a disk refiner comprising trestles for the support of bearing devices for aligned shafts which support a pair of parallel grinding disks said trestles being connected to each other by means of a number of beams, at least two of said beams being arranged above a horizontal plane through said aligned shafts of the grinding disks and at least two of said beams being arranged below said plane, obliqueness of the disks in relation to each other as a result of grinding forces thereby being prevented; ducts arranged in the stand, said ducts adapted to contain a fluid; means for circulating fluid through said ducts; and means for keeping the temperature of the fluid substantially constant, the temperature of the stand thereby being kept substantially constant for avoiding deflections of the stand as a result of temperature differences.
 2. Stand as defined in claim 1, wherein the stand is resiliently supported on a base therefor.
 3. Stand in accordance with claim 1 wherein the beams are parallel with said aligned shafts of the grinding disks and the cross-sectional center of gravity of the stand coincides with the axis of said aligned shafts of the grinding disks.
 4. Stand in accordance with claim 1 wherein said at least two beams arranged above the horizontal plane are detachable from the remaining parts of the stand.
 5. Stand as defined in claim 1, in which the means for keeping the temperature constant includes a source of heat and a thermostat controlling said heat source to maintain the temperature of the circulating fluid at a temperature which is higher than the maximum temperature which during operation in the steady state would arise in any part of the stand without fluid circulation.
 6. Stand in accordance with claim 1, in which a pump is adapted to circulate the fluid through said stand ducts. 